Second System Syndrome
Second System Syndrome is the curse by which a simple system is doomed to be replaced by an excessively abstract, over-engeered, or bloated successor.
You hack together a small simple program to solve a problem.
Congratulations! It's wildly successful. Now you have a community, and the limits of your hasty work are starting to show. Time for a rewrite!
You've been keeping a list of all the features you would like, limitations you would like to surpass, and you want to avoid getting boxed into a corner again, so you design a super abstract architecture.
Fast forward a few weeks, and you're tangled up in abstractions. The features you have built out don't add up to a product-market fit. You're still weeks away from a finished product. Hmm.
The phrase was first coined in the book The Mythical Man-Month.